def log(func):
    def wrapper(*args, **kw):
        print('call >> %s()' % func.__name__)
        return func(*args, **kw)
    return wrapper

@log
def now(*args, **kw):
   print('2015-3-25')
   # print(args, kw)

# 相当于执行了 now = log(now)
now()